It is well known that various mowing attachments can be towed behind a tractor. In most cases the mowing attachment comprises a cutter defined by a plurality of rotary cutter elements connected together in a frame arrangement which may or may not provide pivotal action between each rotary element and the others. Normally the cutter is towed directly behind the tractor and this provides an effective cutting action on level ground where the cutter can be simply pulled centrally and directly behind the tractor.
However, it has been a long standing problem to provide effective cutting action in a ditch to one side of a roadway. In many cases the tractor driver simply drives the tractor in the ditch with the cutter towed behind to provide a cutting action directly behind the tractor.
In some cases, some degree of offset can be provided by moving the draw bar hitch of the tractor to one side since most tractors have the ability to allow the hitch to be moved to respective sides of the center position. However, this amount of offset is very limited and certainly does not allow the tractor to remain on level ground while the cutter is in the ditch.
Specially designed equipment has, therefore, been provided for this function including sickle bars which are carried to one side of the tractor and a ditch swather in which a swathing assembly is mounted at the outer end of a frame unit towed behind the tractor with the ditch swather being pivotal about a horizontal axis along the direction of movement so that it can run on level ground or can pivot downwardly into a ditch. Other apparatus have been used to fixedly maintain a cutter in an offset position relative to the tractor, and again while a certain variance in the offset angle may be permitted, these apparatus do not permit offset mowing on both sides of the tractor, or permit mowing or transport of the cutter directly behind the cutter. The power transmission through the offset angle in many known devices is provided by continuously variable transmission (CVT) joints in the power train. The drawback to CVT joints in the power train is the decrease in life span of the joint with an increase in required angle. Thus a large offset angle reduces the life span of the joint and severely limits the cutter operation hours. Additionally, these special devices are limited in application and relatively expensive.